Capacitor unit

ABSTRACT

A capacitor unit using a plurality of capacitors and which has a long lifetime and is maintenance-free is provided. The capacitor unit has a high reliability even in harsh using conditions of vibration and shock and a high noise resistant property. This capacitor unit includes a capacitor block in which a plurality of capacitors are incorporated into a holder with body portions of the capacitors sandwiched; a control circuit portion including a charging and discharging circuit for charging or discharging this capacitor block; a relay connector for electrically connecting thereof, and a case housing thereof.

TECHNICAL FIELD

The present invention relates to an emergency power supply of electronicequipment using a battery, etc. In particular, it relates to a capacitorunit used for an electric braking system, etc. for electrically brakinga vehicle.

BACKGROUND ART

Recently, from the viewpoint of conservation of global environment orimprovement in fuel consumption, hybrid cars or electric vehicles havebeen rapidly developed.

Furthermore, various functions for controlling vehicles have beenrapidly electronized. Braking of vehicles is also being shifted from aconventional mechanical hydraulic control to electric hydraulic control,and various electric braking systems are proposed.

When an important function such as braking is out of order becausevoltage reduces in a battery used as a power supply or certaincontingencies occur and power is not supplied, hydraulic control cannotbe carried out. Therefore, a redundant system using an emergency powersupply is often provided.

Conventionally, a method using another battery as an emergency powersupply has been proposed. However, a battery has a characteristic ofdeteriorating over time and its expected lifetime is at most five yearswhen it is used for a vehicle.

Furthermore, it is difficult to detect deterioration in the process andto exhibit a function as an emergency power supply when certaincontingencies occur.

Recently, as an emergency power supply substituting for a battery, muchattention has been focused on a capacitor such as an electric doublelayer capacitor. When a capacitor is used in a way in which, forexample, charging is carried out when a system is operating anddischarging is carried out when a system is not operating, the lifetimeof the capacitor can be extended to several times as the lifetime of abattery. Therefore, it is said that a capacitor can withstand the usefor 15 years, that is, a target lifetime of a vehicle.

Furthermore, by monitoring characteristic value of a capacitor such aselectrostatic capacity and internal resistance, it is possible tounderstand the change in the characteristics.

Note here that prior art document information as to such a capacitorunit includes, for example, Japanese Patent Unexamined Publication No.10-189402.

Furthermore, conventionally, a capacitor, other circuit components and acircuit board have been mounted as follows. FIG. 14 is an example of asectional view showing a conventional mounting. In FIG. 14, on circuitboard 501, circuit components 502 constituting a necessary circuitportion are mounted. In general, circuit board 501 is used with the endportion thereof fixed to attaching portion 505 of case 504 by usingscrew 503, etc.

Information on such a conventional technology is disclosed in, forexample, Japanese Utility Model Unexamined Publication No. S63-97286.

SUMMARY OF THE INVENTION

A capacitor unit includes: a capacitor block formed by incorporating aplurality of capacitors into a holder with body portions of thecapacitors sandwiched and electrically connecting the capacitors inseries or in parallel; a control circuit portion including a chargingand discharging circuit for charging or discharging the capacitor block;a relay connector for electrically connecting the capacitor block andthe control circuit portion; and a case housing the capacitor block, thecontrol circuit portion and the relay connector. The control circuitportion includes a circuit board, a circuit component forming thecharging and discharging circuit, a heat radiator for suppressing heatgeneration of the circuit component in charging and discharging, amicrocomputer for detecting and controlling states of the charging anddischarging circuit and the capacitor block, and a connector connectedto an external load. The control circuit portion is incorporated intothe case in a way in which the circuit board is housed in the case in anupright position with respect to the case.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a configuration of an electronic braking system of avehicle in an exemplary embodiment of the present invention.

FIG. 2 is an exterior perspective view showing a capacitor unit in anexemplary embodiment of the present invention.

FIG. 3 is an exploded perspective view showing a main part of thecapacitor unit.

FIG. 4 is a perspective view showing a main part of the capacitor unitwith an upper cover removed.

FIG. 5 is an exploded perspective view showing a main part of a controlcircuit portion of the capacitor unit.

FIG. 6 is a block diagram showing a circuit of the capacitor unit.

FIG. 7 is a perspective view showing a configuration of a leaf springportion of the control circuit portion.

FIG. 8 is a perspective view showing a configuration of a leaf springportion of the control circuit portion.

FIG. 9 is an exploded perspective view showing a shield structure of thecontrol circuit portion of the capacitor unit.

FIG. 10 is a perspective view showing a main part of a shield structureof the control circuit portion of the capacitor unit.

FIG. 11 is a perspective view showing a main part of a shield structureof the control circuit portion of the capacitor unit.

FIG. 12 is a perspective view showing a relay connector of the capacitorunit.

FIG. 13 is a perspective view showing a main part of a connector portionof the capacitor unit.

FIG. 14 is a sectional view showing conventional electronic equipment.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS

A capacitor has a shortcoming that the withstand voltage is low due toits nature. Therefore, in order to obtain a necessary voltage, it isnecessary to use a plurality of capacitors connected in series.Furthermore, depending upon a necessary energy amount, theseries-connected capacitors is required to be used in parallelconnection. In addition, it is necessary to provide a control circuitfor charging and discharging the capacitors.

Although properties of capacitors are being focused, few proposals havebeen made on a structure capable of enduring the lifetime of a vehicle,etc. as a unit of an emergency power supply integrating a plurality ofcapacitors and a control circuit into each other.

Furthermore, conventionally, when circuit components such as a capacitorand various kinds of elements to be attached to a circuit board requireheat radiation, for heat radiation, in general, a heat radiator isattached to a circuit board or circuit components and then circuitcomponents are allowed to be pressure welded to this heat radiator.Thus, heat radiation is effected.

However, in a conventional attaching structure of a circuit board shownin FIG. 14, end portions of the circuit board are fixed to attachingportions of a case. Therefore, when the circuit board is provided with alarge and heavy heat radiator, under using conditions in which largeloads of vibration or shock are applied, stress due to vibration isconcentrated on the attaching portions of the heat radiator or solderingportions of circuit components that are pressure welded thereto, so thatthe soldering portions may be damaged or the circuit board itself may bedamaged.

The present invention is made to solve such problems mentioned above.The present invention contributes to the improvement of the reliabilityand safety of a used system by allowing a capacitor block composed of aplurality of capacitors and a control circuit portion for controllingthe charging and discharging to be integrated as a unit.

Furthermore, the present invention provides electronic equipment inwhich a weight load is not applied to a circuit board and which has ahigh reliability even under harsh using conditions particularly in avehicle, etc. in which vibration or shock is applied

Hereinafter, an exemplary embodiment of the present invention isdescribed with reference to drawings.

FIG. 1 is a view showing a configuration of an electronic controlbraking system of a vehicle in the exemplary embodiment of the presentinvention. In FIG. 1, battery 1 for supplying power and capacitor unit 2as an emergency power supply are electrically connected to electroniccontrol portion 3 for controlling an electronic control braking system,respectively. Furthermore, electronic control portion 3 is alsoconnected to brake pedal 4 and hydraulic control portion 5, and thishydraulic control portion 5 is connected to brake 6 and tire 7.

In the electronic control braking system having such a configuration,when electric power supply from battery 1 is lost due to somecontingencies during operation, a function of electronic control brakingsystem is lost. When such contingencies occur during driving, brake doesnot work, making it impossible to brake a vehicle. In order to preventit, capacitor unit 2 is connected, which is configured to releaseelectric charges accumulated in capacitor unit 2 based on an instructionfrom electronic control portion 3 so as to operate the electroniccontrol braking system and to brake a vehicle when contingencies occur.

This present invention relates to capacitor unit 2. The descriptiontherefor follows.

FIG. 2 is an exterior perspective view showing a capacitor unit 2. FIGS.3, 4 and 5 are exploded perspective views of capacitor unit 2,respectively.

In each drawing, relay connector 13 electrically connects capacitorblock 11 and control circuit portion 12. Connector 14 is electricallyconnected to electronic control portion 3 of the electronic controlbraking system. These are housed in case 15 composed of lower case 15 aand upper cover 15 b.

Herein, firstly, the configuration of capacitor block 11 is described.

Capacitor 16 has, on its upper surface, lead wire 16a having a positivepolarity and lead wire 16b having a negative polarity which extend inthe same direction. In this exemplary embodiment, 28 capacitors areconfigured in a way in which seven series-connected capacitors arearranged in four parallel lines. When allowable voltage per capacitor 16is 2V, in order to be applied to a 14V system, seven capacitors areconnected in series, and in order to secure necessary electric charge,the seven series-connected capacitors are arranged in four parallellines. Thus, an amount of electric charge is increased.

Holder 17 stably retains the above-mentioned 28 capacitors 16 in a wayin which seven series-connected capacitors are arranged in four parallellines. At this time, a plurality of capacitors 16 are assembled by usinga jig, etc. so that the heights of upper surfaces 16 c from which leadwires 16 a and 16 b extend are substantially uniform in 28 capacitors.

Circuit board 18 is provided with a circuit pattern for connecting aplurality of capacitors 16 in a way in which seven series-connectedcapacitors are arranged in four parallel lines. Then, lead wires 16 aand 16 b of capacitor 16 are inserted into and soldered to a solderingland portion of circuit board 18. Circuit board 18 is provided withconnector 19 on the end portion thereof so as to be electricallyconnected to control circuit portion 12. The thus configured capacitorblock 11 is housed in lower case 15 a and fixed thereto with a screw,etc.

Then, control circuit portion 12 is described in detail.

FIG. 6 is a block diagram showing a circuit configuration of thecapacitor unit of the present invention.

Capacitor unit 2 includes a microcomputer for transmitting and receivingvarious signals, capacitor block 11, charging circuit 50 for instructingcapacitor block 11 to charge, discharging circuit 51 for instructingcapacitor block 11 to discharge, back-up detecting means 52 fordetecting voltage output from battery 1, and FET switch 54. Capacitorblock 11 is formed of a plurality of capacitors by using, for example,an electric double layer capacitor capable of rapid charging anddischarging as an auxiliary power supply for supplying electric power tohydraulic control portion 5 via electric control portion 3 when battery1 is in an abnormal state. FET switch 54 enables discharging to electriccontrol portion 3 from capacitor block 11 via OUT terminal 53 whenback-up detecting means 52 detects abnormality in electric voltage.

Then, a structure of control circuit portion 12 is described withreference to FIGS. 3 to 5. In these drawings, components that are notrelated to the present invention are omitted. Although not shown incircuit board 20, a circuit pattern of charging and discharging circuitis provided. In the exemplary embodiment of the present invention, twoFETs 21 a and 21 b as a circuit component for charging, diode 22 a as acircuit component for charging and resistor 22 b are shown. Thesecircuit components are circuit components generating heat in which alarge amount of electric current flows at the time of charging anddischarging. FETs 21 a and 21 b, diode 22 a and resistor 22 b have leadwires fixed to circuit board 20 by soldering, on the rear surface ofwhich a heat radiating portion is formed. The heat radiating portion ispressure welded to heat radiator 23 with an appropriate pressure.

The thus configured control circuit portion 12 is housed in lower case15 a in an upright position. Relay connector 13 is led out from circuitboard 20 and fitted into and electrically connected to connector 19 ofcapacitor block 11. Control circuit portion 12, which is housed in anupright position, is disposed so that a surface on which heat radiator23 and FETs 21 a and 21 b as circuit components for charging, diode 22 aas a circuit component for charging and resistor 22 b are mounted ispositioned at the opposite side to capacitor block 11 with circuit board20 sandwiched therebetween. Thus, a site generating heat by electriccurrent flowing at the time of charging and discharging of capacitorblock 11 can be disposed at a distance from capacitor block 11 withcircuit board 20 as a spacer. In a capacitor unit using a plurality ofcapacitors 16, the performances of capacitors are required to beuniform. The ambient temperature of each capacitor is desired to be asuniform as possible. The exemplary embodiment makes it possible tosuppress variation in temperature in the capacitor portion by heatgenerated at the time of charging and discharging as much as possible.

Heat radiator 23 is provided with two holes 23 a and 23 b to be fixed tolower case 15 a. Furthermore, at the corresponding positions of lowercase 15 a, fixing bosses 24 a and 24 b are formed to be screwed withscrews 24 c and 24 d.

On surface 23 c of heat radiator 23 at the side that is incorporatedinto lower case 15 a, concave holes 23 d and 23 e, which are concentricto holes 23 a and 23 b and fitted into fixing bosses 24 a and 24 b, areformed. Positioning is carried out by concave holes 23 d and 23 e andfixing bosses 24 a and 24 b in attachment.

In this fixing state, circuit board 20 is housed in lower case 15 a inan upright position and outer peripheral surfaces 20 a, 20 b, 20 c and20 d of circuit board 20 are kept in a free state in lower case 15 a.

As mentioned above, in the exemplary embodiment of the presentinvention, since heat radiator 23 is fixed to lower case 15 a butcircuit board 20 is not fixed to lower case 15 a, circuit board 20 canbe kept in a free state. Therefore, even in a case where loads ofthermal expansion and contraction vibration are applied, stress is notapplied on soldering portions of the circuit components mounted oncircuit board 20. Thus, reliability can be expected to be improved.

A method of stable heat radiation of FETs 21 a and 21 b as a circuitcomponent for charging, diode 22 a as a circuit component fordischarging and resistor 22 b to heat radiator 23 is described withreference to FIGS. 7 and 8.

In FIG. 7, leaf spring 25 made of an elastic member such as stainlesssteel, etc. has an approximately rectangular U shape and at the centerthereof, fixing hole 25 a that is directed to heat radiator 23 isprovided. Both end portions are bent. One end portion is elastic piece25 b extending in an arm shape and is provided with R processing portion25 c so as to pressure weld certain positions of body parts of FET 21 aand 21 b, diode 22 a and resistor 22 b. Another end portion is guideportion 25 d that is brought into contact with surface 23 c at the sideof heat radiator 23, which is incorporated into lower case 15 a, in anappropriate length.

Furthermore, although not shown in the drawings, on a surface on whichFETs 21 a and 21 b, diode 22 a and resistor 22 b are pressure welded toheat radiator 23, grease made of silicon, etc. for promoting heatradiation is applied. Pressure welding force by leaf spring 25 is set tothe bearing of 0.1 N to 4.5 N.

Leaf spring 26 shown in FIG. 8 is fabricated by coupling structures ofleaf springs 25. When a plurality of circuit components requiring heatradiation exist (in the exemplary embodiment, four circuit componentsexist), leaf spring 26 in which elastic pieces 26 a are coupled inaccordance with the number of the circuit components is used, therebyenabling pressure welding simultaneously.

Thus, with a pressure welding structure using leaf spring 26, FETs 21 a,21 b and diode 22 a as a circuit component for charging and dischargingand resistor 22 b are fixed to circuit board 20 at the solderingportion. However, the fixing is carried out by just being pressurewelded to heat radiator 23 with an appropriate pressure. Therefore, evenwhen difference in thermal expansion and contraction in each member dueto the change in temperature, etc. occurs, it is possible to relaxstress generating in the soldering portion. Furthermore, by forming leafspring 25 in substantially an approximately rectangular U shape so as toregulate the position with respect to heat radiator 23 by guide surface25 d, distribution in pressure welding force can be reduced. Inaddition, with the use of grease for promoting heat radiation, pressurewelding force itself can be reduced. Furthermore, it is possible topressure weld a plurality of circuit components at the same time by leafspring 26, thus making it possible to reduce man-hour and to unify thepressure welding force.

The pressure welding force is set to 0.1 N to 4.5 N. This pressurewelding force is determined based on a minimum load capable of reliablyreleasing heat to heat radiator 23, and an acceptable stress, etc. ofsoldering portions with respect to vibration on the soldering portionsof lead wires of circuit components to be pressure welded and circuitboard 20 and temperature change. Controlling the pressure welding forcein this range enables more reliable heat radiation and prevention ofdamage in the soldering portion due to vibration and temperature change,etc., which can lead to improvement in the reliability.

Next, a shield structure of control circuit portion 12 is described withreference to perspective views of a main part shown in FIGS. 9, 10 and11.

Various electronic control systems used in vehicles require not onlybasic functional assurance but also strict noise resistance. Themeasurement therefor is a major element of development.

In FIG. 9, a shield case is divided into an upper portion and a lowerportion and includes lower shield case 27 made of metal and upper case28.

Lower shield case 27 is provided with two case fixing pieces 29 a and 29b by allowing the side surface to rise on the internal surface side.

Lower case 15 a is provided with fixing bosses 30 a and 30 b extendingin the positions corresponding to case fixing pieces 29 a and 29 b. Onthe bottom surface of lower shield case 27, holes 31 a and 31 b areformed in the positions concentric with respect to case fixing pieces 29a and 29 b. Furthermore, on the positions corresponding to bosses 24 aand 24 b for fixing heat radiator 23 of control circuit portion 12,holes 32 a and 32 b, through which fixing bosses 24 a and 24 b passes,are formed.

One ground terminal 33 extends from circuit board 20 of control circuitportion 12. Ground terminal 33 includes lead wire 33 a and terminal 33 bat the tip thereof. Opposite end of lead wire 33 a is soldered to aground of circuit board 20.

In the configuration mentioned above, firstly, when lower shield case 27is incorporated into lower case 15 a so that holes 31 a and 31 b oflower shield case 27 are inserted into fixing bosses 30 a and 30 b, casefixing pieces 29 a and 29 b are brought into contact with fixing bosses30 a and 30 b. Then, control circuit portion 12 is incorporated so thatholes 23 a and 23 b of heat radiator 23 are fitted into fixing bosses 24a and 24 b of lower case 15 a, terminal 33 b of ground terminal 33 andcase fixing piece 29 b are together fastened to fixing bosses 30 b witha screw. Another case fixing piece 29 a is fixed to fixing boss 30 awith a screw. In this state, upper shield case 28 is covered, whereby ashield structure is formed. Also in the circuit structure of controlcircuit portion 12, various noise components ought to be provided.However, by further covering an entire portion of control circuitportion 12 with lower shield case 27 and upper shield case 28, highnoise resistant property can be exhibited.

Next, a method for fabricating lower shield case 27 and upper shieldcase 28 is described.

On two side surfaces of upper shield case 28, two guide surfaces 35located at the inside of wall surfaces 34 a and 34 b of lower shieldcase 27 and guide surface 36 located at the outside of wall surfaces 34a and 34 b of lower shield case 27 are provided.

When incorporation is carried out in this state, wall surfaces 34 a and34 b are sandwiched between guide surface 35 and guide surface 36, thusenabling lower shield case 27 and upper shield case 28 to be reliablyfitted into each other.

Furthermore, an interval between guide surfaces 35 and 36 is set tobecome smaller than the thickness of wall surfaces 34 a and 34 b oflower shield case 27 in the direction in which guide surfaces 35 or/and36 become close to each other. Thus, wall surfaces 34 a and 34 b aresandwiched between guide surfaces 35 and 36 with pressed thereby. As aresult, lower shield case 27 and upper shield case 28 can be fabricatedwithout looseness. At the same time, lower shield case 27 and uppershield case 28 can be reliably kept in a short state, enabling highershield performance to be exerted.

Furthermore, on guide surface 35 of upper shield case 28, protrusions 37a and 37 b are formed. On lower shield case 27, holes 38 a and 38 b areformed on the positions corresponding to the protrusions 37 a and 37 b.Thus, it is possible to prevent the shield cases from floating ordisplacing after insertion by semi-fitting or fitting.

Similarly, on two surfaces in the longitudinal direction of lower shieldcase 27, rise pieces 39 a and 39 b are formed. The distance between thetip portions of rise pieces 39 a and 39 b is slightly larger than thedistance between internal surfaces 40 a and 40 b of lower case 15 a tobe inserted.

When lower case 15 a is inserted into lower shield case 27 in thisstate, rise pieces 39 a and 39 b and internal surfaces 40 a and 40 b arepressed into each other, and thus it is possible to prevent loosenessand vibration of the lower shield case. Similarly, also on two surfacesin the longitudinal direction of upper shield case 28, rise pieces 41 aand 41 b are provided, and pressed into internal surfaces 42 a and 42 bof upper cover 15 b. Thus, it is also possible to prevent looseness andvibration of upper shield case 28.

Next, in FIG. 10, on lower shield case 27 or upper shield case 28 (inthis exemplary embodiment, the case of lower shield case 27 isdescribed), piece 43 that is folded outwardly from the side surface isformed. It is led to the outside of case 15 in a state in which shieldcase 27 is incorporated into case 15. At the time of being incorporatedinto a vehicle, etc. by using piece 43, by fixing it to a ground of anexternal load or a chassis of ground potential with being electricallyconducted thereto. Thus, a control circuit system can be shieldedreliably.

Furthermore, as shown in FIG. 11, piece 44, which is folded toward theside surface of lower shield case 27, is further folded in the middlethereof so as to form folding portion 44 a. In the center portion offolding portion 44 a, screwing hole 44 b is formed. On the side surfaceof lower case 15 a, a plurality of nuts 45 with an appropriate nominaldiameter are formed by press-fitting or insert molding. Herein, screwinghole 44 b of folded piece 44 is disposed in a dimensional relation inwhich screwing hole 44 b corresponds to screw hole of nut 45 in a finalproduct after the shield case is incorporated into the case 15. In thisstate, bracket 46 used for being attached to a vehicle is fastenedtogether with nut 45. This makes it possible to secure ground potentialof the shield case at the same time of working of attaching a bracket toa vehicle, thus enabling a control circuit system to be shieldedreliably.

FIG. 12 shows relay connector 13 for electrically connecting circuitportion 12 and capacitor block 11. In relay connector 13, for example,when 5A of current capacity is required, electric wires (+ and −) andconnector terminals are required to have 5A or more of current capacity.In such a case, however, electric wire having a large wire diameter orconnector terminal having a large size are required, which may lead toan increase of occupied space in a product. In the configuration of thisexemplary embodiment, two electric wires 47 whose current capacity is2.5A or more and about 3A or less and two connector terminals 48 arearranged in parallel and used. With this configuration, although thenumber of connector portions is increased, small sized connector can beused. Furthermore, a plurality of electric wires 47 with small capacityor connector terminals 48 can be arranged in parallel.

Thus, the dimension of relay connector 13 in the up-and-down directionand back and forth direction can be reduced although the dimension inthe parallel direction is increased. As is apparent from the perspectiveview shown in FIG. 4, since there is room in space in the paralleldirection, an entire size can be downsized.

FIG. 13 is a perspective view showing a main part of a periphery ofconnector 14. The protection of the connector is described. Sinceconnector 14 is fitted into a connector of an external load (not shown),it is protruded outwardly in a state of a final product from theviewpoint of workability. On lower case 15 a, protection wall 49 forprotecting connector 14 is provided so as to cover the outer peripheryof connector 14. Furthermore, protection wall 49 does not cover only asite of fitting rock portion 14 a provided in connector 14. This isbecause this configuration makes it easy to carry out fitting work andmakes it possible to visually check a fitting state. This makes itpossible to prevent the connector from being damaged due to handling ofa final product, and certain contingencies occurring at the time of, forexample, manufacturing process, delivery, attachment to a vehicle, andthe like.

In order to solve the above-mentioned problems, the capacitor unit ofthe present invention has a control circuit for charging and discharginga capacitor arbitrarily and a means for detecting a state of a capacitorblock, whereby the performance of the capacitor can be optimized. At thesame time, a state of deterioration can be also monitored. In addition,the control circuit is incorporated into a case in an upright position,whereby it is possible to provide a suitable capacitor unit withimproved space efficiency.

Furthermore, according to the capacitor unit of the present invention, asite generating heat by an electric current flowing at the time ofcharging and discharging the capacitor block can be located apart fromthe capacitor block with a circuit board disposed as a separator.

Furthermore, according to the capacitor unit of the present invention,since a heat radiator is used to be fixed to the case, it is possible tokeep the circuit board constituting a control circuit portion to be in afree state without being fixing it to the case. As compared with aconfiguration in which the circuit board is directly fixed to the casewith a screw, even when thermal expansion and contraction occurs due totemperature change, stress is not applied to soldering portions, etc. ofcircuit components constituting the circuit board. Therefore, it ispossible to improve the reliability of the control circuit portion.

Furthermore, according to the capacitor unit of the present invention,when the heat radiator is fixed to the case, the position can beregulated.

Furthermore, according to the capacitor unit of the present invention,since the control circuit portion is fixed by using fixing holes of theheat radiator and fixing bosses of the case, the periphery of thecircuit board of the control circuit portion can be kept to be in a freestate in the case. Even under using conditions in which loads ofvibration and shock, etc. are applied, a stress is not applied to thesoldering portions of the circuit components to thus improve thereliability.

Furthermore, according to the capacitor unit of the present invention,circuit components requiring heat radiation of the control circuitportion are pressure welded to the heat radiator that is attached to thecircuit board with a pressure suitable for heat radiation, whereby theincrease in temperature of the circuit components is suppressed at thetime of controlling charging and discharging, and the circuit componentsare prevented from being out of order. Thus, the capacitor unit of thepresent invention can be used for a long time.

Furthermore, according to the capacitor unit of the present invention,pressure is maintained appropriately by the pressure welding by a leafspring, thereby relaxing a stress to the soldering portion of thecircuit components due to thermal expansion and contraction andvibration. At the same time, secure heat radiation can be carried out.

Furthermore, according to the capacitor unit of the present invention,the pressure welding force of the circuit component can be stabilizedand stable heat radiation effect can be achieved.

Furthermore, according to the capacitor unit of the present invention,the circuit components for charging and discharging to be pressurewelded to the heat radiator can be mounted stably, which can lead to theimprovement of the reliability of charging and discharging circuit.

Furthermore, according to the capacitor unit of the present invention,heat radiation of the circuit components can be promoted at the time ofcontrolling charging and discharging of the capacitor unit, temperatureincrease can be suppressed with relatively low pressure welding force,and the disorder of circuit components can be prevented. Thus, thecapacitor unit of the present invention can be used for a long time.

Furthermore, the capacitor unit of the present invention is determinedbased on a minimum load capable of reliably releasing heat to the heatradiator and an acceptable stress of the soldering portion with respectto the vibration on the soldering portions of the lead wires of thecircuit components and the circuit board and temperature change, etc.Managing in this range enables more reliable heat radiation andprevention of cracks in the soldering portion due to vibration andtemperature change, etc.

Furthermore, according to the capacitor unit of the present invention,when a plurality of circuit components are pressure welded to the heatradiator, attachment can be simplified and pressure welding force can bemade uniform.

Furthermore, according to the capacitor unit of the present invention, ashield case is fixed to the case together with a ground of the circuitboard, whereby the shield case can be fixed to the case reliably and atthe same time the shielding effect can be improved by dropping theground onto the circuit board. Thus, the reliability of the controlcircuit portion can be improved.

Furthermore, the capacitor unit of the present invention can befabricated easily without using a fixing screw, etc. and has anexcellent shielding property.

Furthermore, the capacitor unit of the present invention has aconfiguration in which looseness in fitting when the capacitor unit isfitted into the lower shield case is prevented. Furthermore, thefabricating property and the shielding property can be improved.

Furthermore, according to the capacitor unit of the present invention, aguide surface provided on the upper shield case and a wall surface ofthe lower shield case have one or more pairs of fitting portions of ahole and a boss on the positions corresponding to each other, so thatthe positioning can be carried out in a state in which when the uppershield case is incorporated into the lower shield case. Thus,fabricating property can be improved.

Furthermore, according to the capacitor unit of the present invention,lower shield case or/and upper shield case have, on the side surfacethereof, a rise portion whose dimension is slightly larger than thedimension of the internal surface of the housing portion of the case,thus enabling the shield case to be housed in the case withoutlooseness. Therefore, it is possible to prevent the occurrence ofabnormal noise during driving, etc. by excluding looseness between theshield case and the housing.

Furthermore, according to the capacitor unit of the present invention,on the lower shield case or upper shield case, a piece folded outwardlyfrom the side surface thereof is provided. The piece is led to the sidesurface of the case and connected to a ground of an external loadthrough a ground connection. By allowing the shield case and the groundof the external load to be in the same potential, the shield performancecan be stabilized.

Furthermore, according to the capacitor unit of the present invention,the shield case can be dropped onto the ground of a vehicle body via anattachment bracket to a vehicle. Thus, the shield performance can bestabilized.

Furthermore, according to the capacitor unit of the present invention, arelay connector for electrically connecting the capacitor block and thecontrol circuit portion uses a plurality of connectors having currentcapacity smaller than that necessary for charging and discharging.Therefore, by using a small-sized connector and an electric wire havinga small wire diameter, consequently, space efficiency and workabilitycan be improved.

Furthermore, according to the capacitor unit of the present invention,it is possible to prevent the connector from being damaged due to dropor shock to the connector portion when the capacitor unit is fabricated,delivered, attached to a vehicle. Thus, the quality of the controlcircuit portion can be stabilized.

Furthermore, according to the capacitor unit of the present invention,the leaf spring is processed in a rectangular U shape. One end of theleaf spring has a surface that is brought into contact with a rearsurface of the heat radiator and another end is formed so that thecircuit components are pressure welded to the heat radiator. The centerportion is fixed to the heat radiator with a screw. This configurationmakes it possible to stabilize the pressure welding force of the circuitcomponents and to realize a stable heat radiating effect.

As mentioned above, the present invention provides a capacitor unitcapable of retaining a plurality of capacitors connected in series or inparallel with high reliability and capable of optimizing the propertiesof the capacitors by providing a charging and discharging circuit. Inaddition, the present invention can provide a capacitor unit havingvarious considerations with respect to a structure for integrallyincorporating the control circuit portion and a shield structure andhaving a high reliability and excellent usability.

Furthermore, the present invention can provide a capacitor unit with aconsiderably improved reliability, which can carry out heat radiationreliably and in which a stress is not applied to the soldering portionsof the circuit components even under using conditions where loads ofvibration or shock are applied.

INDUSTRIAL APPLICABILITY

A capacitor unit of the present invention can retain a plurality ofcapacitors connected in series or in parallel with high reliability andcan optimize the properties of the capacitors by providing a chargingand discharging circuit. Therefore, the capacitor unit of the presentinvention is suitable for a use as a capacitor unit for an auxiliarypower supply in an electric control braking system of a vehicle, etc.Furthermore, according to the capacitor unit of the present invention,the heat radiator is fixed to the case by screwing and the circuit boardis allowed to be in a free state in the case. Thus, the capacitor unitof the present invention can provide a retaining structure capable ofconsiderably improving the reliability in which a stress is not appliedto a soldering portion of the circuit component. Thus, the capacitorunit of the present invention is suitable for a use in the applicationrequiring resistance to vibration and thermal shock.

1. A capacitor unit comprising: a capacitor block formed byincorporating a plurality of capacitors into a holder with body portionsof the capacitors sandwiched and electrically connecting the capacitorsin series or in parallel; a control circuit portion including a chargingand discharging circuit for charging or discharging the capacitor block;a relay connector for electrically connecting the capacitor block andthe control circuit portion; and a case housing the capacitor block, thecontrol circuit portion and the relay connector, wherein the controlcircuit portion comprising: a circuit board; a circuit component formingthe charging and discharging circuit; a heat radiator for suppressingheat generation of the circuit component in charging and discharging; amicrocomputer for detecting and controlling states of the charging anddischarging circuit and the capacitor block; and a connector connectedto an external load; and wherein the control circuit portion isincorporated into the case in a way in which the circuit board is housedin the case in an upright position with respect to the case.
 2. Thecapacitor unit according to claim 1, wherein the control circuit portionis housed in the case in a way in which a surface on which the circuitcomponent forming the charging and discharging circuit and the heatradiator are mounted is located opposite side to the capacitor block. 3.The capacitor unit according to claim 1, wherein the heat radiator has afixing hole, the case has a fixing boss corresponding to the hole formedon the heat radiator, and the hole and the boss are screwed to be fixedin the case.
 4. The capacitor unit according to claim 3, wherein aconcave hole capable of being fitted into a periphery of the fixing bossformed in the case is provided on a side of a case surface of the holeof the heat radiator.
 5. The capacitor unit according to claim 4,wherein a periphery of the circuit board, which is fixed by the hole ofthe heat radiator and the fixing boss, is maintained in a free state inthe case.
 6. The capacitor unit according to claim 1, wherein thecircuit component requiring heat radiation is pressure welded to theheat radiator with a pressure suitable for heat radiation.
 7. Thecapacitor unit according to claim 6, wherein the circuit component ispressure welded to the heat radiator by using an elasticity of a leafspring attached to the heat radiator.
 8. The capacitor unit according toclaim 7, wherein the leaf spring is processed in a rectangular U shape,in which one end has a surface that is brought into contact with a rearsurface of the heat radiator and another end has a pressure weldingportion that allows the circuit component to be pressure welded to theheat radiator, and a center portion thereof is fixed to the heatradiator with a screw.
 9. The capacitor unit according to claim 8,wherein the leaf spring has a guide portion for guiding a verticaldirection of the circuit component so that the circuit component is notfallen in a right and left direction.
 10. The capacitor unit accordingto claim 8, wherein the circuit component requiring heat radiation ispressure welded to the heat radiator via grease for promoting heatradiation.
 11. (canceled)
 12. The capacitor unit according to claim 8,wherein the leaf spring is connected so that a plurality of the circuitcomponents can be pressure welded simultaneously.
 13. The capacitor unitaccording to claim 1, wherein: the control circuit portion isincorporated into the case with covered with a shield case which aredivided into an upper shield case and a lower shield case; the lowershield case has one or more fixing pieces to be fixed to the case, thefixing piece being obtained by allowing a part of the lower shield caseto rise; the case has a screw-fixing boss at the position correspondingto the fixing piece; a ground terminal extends from a ground of thecircuit board; and the ground terminal and the lower shield case aretogether fastened to the fixing boss with a screw.
 14. The capacitorunit according to claim 13, wherein the upper shield case has a guidesurface positioned on an inside of a wall surface of the lower shieldcase and a guide surface positioned on an outside of a wall surface ofthe lower shield case; and the upper shield case and the lower shieldcase are fitted into each other at the guide surface.
 15. The capacitorunit according to claim 13, wherein the upper shield case has a firstguide surface and a second guide surface; the first guide surface andthe second guide surface or both are processed to be deformed in thedirection in which the first guide surface and the second guide surfacebecome close to each other, thereby preventing looseness in fitting whenthey are fitted into the lower shield case.
 16. The capacitor unitaccording to claim 15, wherein at least one of the first guide surfaceand the second guide surface and a wall surface of the lower shield casehave one or more pairs of fitting portions of a hole and a boss on eachcorresponding position, thereby regulating the positions thereof whenthey are incorporated into each other.
 17. The capacitor unit accordingto claim 13, wherein the lower shield case or/and the upper shield casehave, on the side surface thereof, a rise whose dimension is slightlylarger than a dimension of an internal surface of a housing portion ofthe case, and the shield case is housed in the case without looseness.18. The capacitor unit according to claim 13, wherein the lower shieldcase or the upper shield case has a piece that is folded outwardly fromthe side surface, and the piece is led to the side surface of the caseand connected to a ground of an external load through a groundconnection.
 19. The capacitor unit according to claim 18, wherein anouter peripheral surface of the case is provided with a screw fixing nutfor fixing a bracket to be attached to a fixed body; and the piece thatis folded outwardly from the side surface of the lower shield case isfixed to the bracket together with the screw fixing nut of the case. 20.The capacitor unit according to claim 1, wherein a connector forelectrically connecting the capacitor block and the control circuitportion is configured by using a plurality of connectors having currentcapacity that is smaller than the current capacity necessary forcharging and discharging.
 21. The capacitor unit according to claim 1,wherein a connector that is electrically connected to an outside of thecontrol circuit portion is protruded from a part of the case and theperiphery thereof is provided with a protection wall formed on the case.